The invention relates to a device for equalizing the hot water and cold water pressures in a hot water faucet for sanitary use, such as a thermostatic faucet.
It also relates to the faucet, particularly thermostatic, equipped with said equalizing device.
Conventionally, a so-called thermostatic faucet comprises:
a body that locally delimits a so-called mixing chamber fed at least indirectly by a cold water inlet pipe, and at least indirectly by a hot water inlet pipe,
an outlet for mixed water having a predetermined temperature,
a device for adjusting the flows of cold water and hot water to obtain a so-called outgoing water at the appropriate temperature, which device comprises an element that, being sensitive to the temperature of the water in the mixing chamber, controls the movement of a slide valve that adjusts the cross sections of the passages of the hot water and cold water inlets as a function of a set-point value.
Thus, when the water in the mixing chamber exceeds the set-point temperature, the sensitive element reduces the cross section of the passage of the hot water inlet, and at the same time increases the cross section of the passage of the cold water inlet, and vice versa if the temperature is lower than the set-point temperature.
The sensitive element necessarily has an inertia in order to prevent the system from being constantly unstable.
The maintenance the temperature of the water flowing out of the faucet depends primarily on the fluctuations in the inflows of cold water and hot water, and hence on the stability of the cold water and hot water pressures, which inevitably affect the flows.
There is a known pressure equalizing system installed upstream from the mixing chamber of a thermostatic faucet (FR-A-2.636.705), whose purpose is to attenuate the pressure variations.
This device is constituted by a plunger whose ends are hollow so as to form a so-called cold water chamber through which the cold water passes and a so-called hot water chamber through which the hot water passes, these chambers being connected upstream and downstream by radial openings.
The plunger acts like a slide valve.
There is also a known device (U.S. Pat. Nos. 5,341,987 and 3,724,480) for equalizing the hot water and cold water pressures in a faucet of this type comprising, upstream from a thermostatic unit:
a moving element constituted by a membrane whose plane determines the plane of symmetry of two chambers, and a control rod passing through the membrane at its center, to which rod said membrane is attached,
valves mounted on each of the two ends of the common control rod, which cooperate with seats,
means for translationally guiding the control rod,
a non-return valve installed in each of the outlets of the chambers.
One drawback of this system is low sensitivity and also a non-negligible risk of jamming after a period of disuse.
One of the objects of the invention is to notably improve the safety of hot water faucets for sanitary use, such as thermostatic faucets.
To this end, the subject of the invention is an equalizing device of the type mentioned above, characterized in that the guiding means are located at each of the ends of the control rod and have guiding surfaces that are smaller than the cross-section of the valve and/or the control rod.